Anti-mold and anti-bacteria air filter

ABSTRACT

The present invention provides an air filter that is excellent in anti-molding and anti-bacterial functions. The anti-mold and anti-bacteria air filter is formed from fabric knitted and woven with a warp and/or a weft made of filiform thermoplastic resin including the organic anti-molding agent and filiform thermoplastic resin including the inorganic anti-bacterial agent. It is also possible to form multi-woven fabric knitted and woven with a warp made of filiform thermoplastic resin including the organic anti-molding agent and the filiform thermoplastic resin including the inorganic anti-bacterial agent.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.09/336,979, filed Jun. 21, 1999, now U.S. Pat. No. 6,165,243.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to anti-mold and anti-bacteria air filter.

2. Description of the Prior Art

Recently, interior and other goods such as clothes, bedding, furniture,carpets and so on have been treated to prevent mold, miscellaneousgerms, etc. from proliferating because a comfortable life environmentbecomes more preferable and because mold, miscellaneous germs, etc.become more dislikable. The preference is not limited to such goods thatpeople may touch directly, but extended to an air filter of an aircleaner or an air conditioner that is necessary for the human lifenowadays. Thus, it is attempted to add anti-molding and anti-bacterialfunctions to the air filter so as to keep air clean.

This type of air filter is usually made of woven and knitted fabriccomposed of thermoplastic resin monofilaments of which anti-molding,anti-bacterial and other agents are mixed in the raw thermoplasticresin. The monofilaments, formed by melt extrusion, are knitted and/orwoven as a warp and a weft resulting in the fabric for the air filter.

It is known that such organic anti-molding agent includes, for example,a VINYZENE anti-molding agent, a zinc pyrithione anti-molding agent, aPREVENTOL anti-molding agent, and so on, any of which is anti-bacterialmainly against mold and yeast. It is known that such inorganicanti-bacterial agent includes silver nitrate, silver sulfate, silverchloride and zeolite or silica gel that carries silver, copper, zinc andtin, any of which is effectively anti-bacterial against bacteria.

However, when both organic anti-molding and inorganic anti-bacterialagents are used in the same system, antagonism between these agentsoccurs such that the organic agent bleeding from a monofilament surfacecoats the inorganic agent, which functions anti-bacterially with theexistence on the surface of the monofilament, or neutralizes a metal ionof the inorganic agent. There was a problem that air filter could nothave both anti-molding and anti-bacterial functions satisfactorily.

3. Problem to be Solved by the Invention

It is the object of the present invention to provide an air filter thatis superior in anti-molding and anti-bacterial characteristics so as tosolve the above described problem.

SUMMARY OF INVENTION

The present invention, as means to solve the above described problem,provides an anti-mold and anti-bacteria air filter that is formed fromfabric knitted and woven with a warp and/or a weft made of filiformthermoplastic resin including the organic anti-molding agent andfiliform thermoplastic resin including the inorganic anti-bacterialagent. Therefore, the present invention is characterized by the fabricknitted and woven with a warp, with a weft, or with a warp and a weftmade of two kinds of filiform thermoplastic resin including either, butnot both, the anti-molding agent or the anti-bacterial agent.

It is also possible to form multi-woven fabric knitted and woven with awarp made of the filiform thermoplastic resin including the organicanti-molding agent and the filiform thermoplastic resin including theinorganic anti-bacterial agent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an air filter for an air conditioner of anembodied example of the present invention.

FIG. 2 is a perspective view of a complex monofilament with a verticalcross section.

FIG. 3 is a plan view of an embodied example of plain weave.

FIG. 4 is a plan view of an embodied example of raschel knitting.

FIG. 5 is a plan view of an embodied example of a honeycomb weavestructure fabric woven with a honeycomb weave structure.

FIG. 6 is a cross sectional view taken along line X—X of FIG. 5.

FIG. 7 is a cross sectional view taken along line Y—Y of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENT

A preferred embodiment is described with the drawings below. FIG. 1shows an air filter 10 for a home air conditioner of an embodied exampleof the present invention. The air filter 10 has a thickness of 2-3 mmand can be removed from and slid into an air-filter slot of the airconditioner. The air filter 10 comprises a frame 12 and four fabrics 14fixed into four windows formed by the frame 12. The air filter 10 is anembodied example of the present invention. Thus, an air filter of thepresent invention may apply and be formed in a desired form for othermodels of air conditioners, air cleaners and so on.

Thermoplastic resin used for the anti-mold and anti-bacteria air filterof the present invention may be polyolefin resin, polyester resin,polyarnide resin, polyacryl resin, polystylene resin, polyvinylchlorideresin and so on. The polyolefin resin is preferable because it isrelatively inexpensive but keeps a stable quality in a continuousproduction process. The polyolefin resin, for example, may be resinmaterial made of one or more of polypropylene, high densitypolyethylene, mid density polyethylene, low density polyethylene,straight chain low density polyethylene, ethylene-propylene copolymer,ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer andso on. The resin material made of polypropylene is, in particular,preferably used because a filament made of the material is superior inmechanical strength.

The organic anti-molding agent used for the present invention, forexample, may be but not be limited to any of the following known agents:a VINYZENE anti-molding agent such as 10, 10′-oxybisphenoxyarsine, azinc pyrithione anti-molding agent such as zinc-2-pyridinethiol-1-oxide,and a PREVENTOL anti-molding agent such as N-(fluorodichloro-methylthio)phthalimide, N-dimethyl-N′-phenyl-(N′-fluorodichloromethylthio)sulfamide. The organic anti-molding agent has an effectiveanti-bacterial function mainly to mold and yeast.

A suitable concentration of the above described organic anti-moldingagent ranges from 0.01 to 5 weight percent to the thermoplastic resin,more preferably, from 0.1 to 1 weight percent. If the concentration ofthe agent is less than 0.01 weight percent, its anti-molding functionmay not be enough. If it exceeds more than 5 weight percent, theanti-molding function may not be increased with an increase of theconcentration and the agent may bleed to cause a problem.

The inorganic anti-bacterial agent used for the present invention, forexample, may be but not be limited to any of the following knownmaterials: silver nitrate, silver sulfate, silver chloride and zeoliteor silica gel that carries silver, copper, zinc and/or tin. Theinorganic anti-bacterial agent is effectively anti-bacterial mainly tomiscellaneous germs and/or bacteria.

A suitable concentration of the above-described inorganic anti-bacteriaagent ranges from 0.1 to 5 weight percent to the thermoplastic resin,more preferably, from 0.5 to 2 weight percent. If the concentration ofthe agent is less than 0.1 weight percent, its anti-bacterial functionmay not be enough. If it exceeds more than 5 weight percent, theanti-bacterial function may not be increased with an increase of theconcentration and excess amount of the agent gives an economicaldisadvantage.

The filiform member made of the above described thermoplastic resinmixed with the above described organic anti-molding agent and the abovedescribed inorganic anti-bacterial agent may be formed in various formssuch as monofilament, mutifilament, flatyarn, splityarn and so on. Thefiliform member may be formed by a known forming method and preferablybe formed in the monofifament form because it is easy to form andbecause the formed monofilament keeps a high strength.

The above described monofilament may preferably be a blade-sheath(core-clad) type of complex monofilament 20 because this type ofmonofilament keeps the high strength even though it includes the agent(FIG. 2). Therefore, the complex monofilament 20 has a blade (or core)member 24 positioned around the center in a cross section cutperpendicular to the longitudinal direction 22 of the monofilament and asheath (or clad) member 26 formed to surround the blade member 24wherein the organic anti-molding agent or the inorganic anti bacterialagent is included only in the sheath member 26 but not included in theblade member 24.

The complex monofilament is formed with a complex monofilament formingapparatus that has a complex nozzle of a blade-sheath structure, whichhas coaxial dual discharge openings and extruders, by melting andextruding a blade (or core) composition and a sheath (or clad)composition through the complex nozzle, by drawing with various types ofheat drawings such as a hot air oven, a hot roller, a water bath and soon after cooling, and by treating in relaxation treatment. The bladesheath type of complex monofilament is preferably formed with the sheathcomposition including the agents. It is preferable not to mix theinorganic anti-bacteria agent with the blade or core composition so asto hold the mechanical strength and elasticity in the core. Further, itmay improve the anti-molding function per the organic anti-molding agentto mix the organic anti-molding agent with the sheath composition and tofacilitate the agent's moving toward the surface of the monofilament.Although the blade composition and the sheath composition could be thesame or different, it is preferable to have the same material in orderto improve adhesivity between the blade or core and the sheath or clad.It is also preferable to have a weight ratio between the bladecomposition and the sheath composition ranging from 1/1 to 4/1.

FIG. 3 shows a relationship between a warp 32 and a weft 34 in plainweave 30 as an example. The warp 32 or the weft 34 comprises singlestring. The warp 32 is woven in a longitudinal direction while the weft34 is woven in a width direction at right angles to the longitudinaldirection. FIG. 4 shows a relationship between a warp 42 and a weft 44in raschel knitting 40 as an example. The warp 42 or the weft 44comprises single string.

A fabric woven and knitted with warps and/or wefts made of (A) filiformthermoplastic resin including the organic anti-molding agent and (B) thefiliform thermoplastic resin including the inorganic anti-bacterialagent is used for the air filter of the present invention.

The filiform resins (A) and (B) may be mixed at any weight ratio for thepurpose to obtain necessary anti-molding and anti-bacterial functions.The following combinations, for example, may be applied in accordancewith the present invention: (A)/(B), (B)/(A), (A)/(A+B), (B)/(A+B),(A+B)/(A), (A+B)/(B) and (A+B)/(A+B), where (A)/(B) means that (A) is aweft/(B) is a warp.

However, using (A) and/or (B) as a weft in a production process maycause deterioration of productivity because it is necessary to exchangethe beam warped with (A) and/or (B) at the time of starting to produceanother kind of product. Thus, it is preferable to use as a weft amonofilament that is used in a general production and does not includeeither anti-molding or anti-bacterial agent and to use the monofilamentthat includes (A) and/or (B) as a warp so as to form multi-woven wovenand knitted fabric with a multi-woven woven and knitted machine. Suchconfiguration may enable to improve the productivity and lower the costbecause of reduction of the work load of exchanging the warped beam.Thus, an anti-molding and anti-bacterial air filter that has enoughanti-molding and anti-bacterial functions and potential to lower thecost because of the high productivity may be obtained.

The woven and knitted texture of the woven and knitted fabric mentionedabove can be any type of texture. If the fabric is a woven fabric, forexample, plain weave, twill weave, gauze elastic webbing, gauze weave,leno weave, etc. may be adopted. If the fabric is a knitted fabric, forexample, tricot knitting, milanese knitting, raschel knitting, etc. maybe adopted.

However, a honeycomb weave structure (FIGS. 5, 6 and 7) of filiformmember with the fineness ranging from 80 to 500 dr is preferable becauseof its elasticity, flexibility, permeability, dust removability anddimensional stability required for the air filter. The honeycomb weavestructure is defined as “derivative weave structure with woven honeycombconcave-convex texture on the surface. It may be called MASUORI.” in thetextile terms (the textile chapter) of Japan Industrial StandardJIS-L0206.

FIG. 5 shows a plan view of a honeycomb weave structure fabric wovenwith a honeycomb weave structure. In the figure, “A” and “A”′ stand forlengths of edges of each honeycomb weave structure unit. FIG. 6 shows across sectional view taken along line X—X of FIG. 5. It is clear that awarp 52 and a weft 54 are woven to form concave-convex structure onfront and back sides of the fabric. The figure also shows B—B and C—Cline-positions 56, 58 and their relationship with the edge length A.FIG. 7 shows a cross sectional view taken along line Y—Y shifted A′/2from the line XX. Likewise, the figure illustrates the warp 52 and theweft 54, and B—B and C—C line-positions 60, 62 and their relationshipwith the edge length A.

The honeycomb weave structure may be formed continuously with a Sulzerweaving machine and be characterized by a three dimensional structurewith concave-convex front and back surfaces. It is important that theair filter of the present invention has a weaving concentration of aweft and a warp strings ranging from 30 to 75 stitches per inch.

Without departing from the spirit and scope of the present invention,usually-used additives such as an antioxidant, a UV-absorbent, a lightstabilizer, a dispersant, a lubricant, an antistatic agent, a pigment,an inorganic filler, a flame retardant, a cross linking agent, a foamingagent, a nucleus forming agent and so on may be mixed with thethermoplastic resin of the present invention.

EXAMPLE 1

An anti-molding monofilament and an anti-bacteria monofilament wereformed with a extruding machine by melt-extruding a composition of 0.5weight percent of anti-mold agent (10, 10′-oxybisphenoxyarsine) to thepolypropylene (MFR=1.2 g/10 min., Tm=161° C.) and a composition of 1weight percent of silver zeolite as anti-bacteria agent to thepolypropylene (MFR=1.2 g/10 min., Tm=161° C.), respectively. Theextruded monofilaments were drawn about at the factor of 8 with a hotair oven type of drawing machine after cooling and then treated in heatrelaxation to obtain the anti-molding monofilament and theanti-bacterial monofilament with the fineness of 150 dr.

A weft with the fineness of 150 dr was prepared from above mentionedpolypropylene. A honeycomb weave structure fabric having a density of60×60 stitches per inch and the honeycomb weave structure unit with eachedge length of 5.2 mm and thickness of 2.2 mm was formed with a multiweaving machine by weaving with the polypropylene weft and thealternative warp of the anti-molding monofilament and the anti-bacterialmonofilament. The fabric was applied to an air filter (Example 1) as anembodiment of the present invention.

COMPARATIVE EXAMPLE 1

A composition of 0.5 weight percent of anti-molding agent (10,10′-oxybisphenoxyarsine) and 1 weight percent of silver zeolite asanti-bacterial agent to the polypropylene (MFR=1.2 g/10 min., Tm=161°C.) was used to form a monofilament. An air filter (ComparativeExample 1) was formed in the same manner as described in Example 1except using this monofilament as a warp.

COMPARATIVE EXAMPLE 2

The polypropylene (MFR=1.2 g/10 min., Tm=161° C.) was used to form amonofilament. An air filter (Comparative Example 2) was formed in thesame manner as described in Example 1 except using this monofilament asa warp.

The above mentioned air filters were tested for anti-molding andanti-bacterial capability as described bellow. The results aresummarized in Tables 1 (a) and (b).

Testing bacteria: Aspergillus niger as Eumycetes and coliform bacillusas bacillus were used.

Preparation: The Eumycetes was pre-cultured in potato dextrose agarmedium at 27° C. for one week. The bacillus was pre-cultured in standardagar medium at 35° C. for 48 hours. The testing bacteria liquid wasprepared with the pre-cultured bacteria and phosphate buffered saline.

Process: In accordance with the disk method, the following steps weretaken.

1. A piece of filter paper was impregnated with the testing bacterialiquid (0.5 ml).

2. The filter paper was placed on a specimen statically.

3. The filter paper on the specimen was put in a culturing container andthe bacteria were cultured for a prescribed period of time.

4. The filter paper on the specimen was taken out of the container.

5. The filter paper was picked up of the specimen.

6. The filter paper was thrown into 5 ml of sterilized water (ten timesdilution) and the mixture was stirred.

7. Supernatant liquid of the mixture was smeared in the same culturemedia as used in the pre-culture.

8. The bacteria were cultured in the same manner as described in thepre-culture.

9. Each living bacteria was counted and the number of bacteria in 1 mlof the supernatant liquid was calculated.

TABLE 1 (a) Bacteria Aspergillus Niger Time START 24 HOURS 48 HOURS 72HOURS Example 1 1.4 × 10⁶ 9.0 × 10⁴ 5.0 × 10⁴ 2.0 × 10³ Comparative 1.4× 10⁶ 3.0 × 10⁵ 1.0 × 10⁵ 1.0 × 10⁴ Example 1 Comparative 1.4 × 10⁶ 3.0× 10⁵ 1.0 × 10⁵ 1.0 × 10⁵ Example 2

TABLE 1 (b) Bacteria Coliform Bacillus Time START 24 HOURS 48 HOURS 72HOURS Example 1 5.6 × 10⁶ 1.1 × 10⁶ 2.0 × 10⁵ 1.0 × 10³ Comparative 5.6× 10⁶ 1.8 × 10⁶ 6.0 × 10⁵ 1.0 × 10⁵ Example 1 Comparative 5.6 × 10⁶ 2.7× 10⁶ 1.6 × 10⁶ 1.0 × 10⁶ Example 2

It is confirmed that the air filter of Example 1 worked effectively inanti-molding and anti-bacterial functions from Tables 1 (a) and (b).

Achievement

The air filter of the present invention has excellent anti-molding andanti-bacterial functions since the anti-molding agent and ananti-bacterial agent are mixed separately with thermoplastic resin so asto prevent the antagonistic action. It also has high and stableproductivity and flexibility as filiform member, and high strength.Further, the honeycomb weave structure, as a filter structure, made offiliform member of a specific fineness has excellent elasticity,flexibility, permeability, removability and dimensional stabilityrequired for the air filter. Thus, the air filter quite effective withrespect to productivity and desired functions was obtained according tothe present invention.

What is claimed is:
 1. A fabric used for an anti-mold and anti-bacteriaair filter, said fabric comprising filiform thermoplastic resinincluding an organic anti-molding agent and filiform thermoplastic resinincluding an inorganic anti-bacterial agent; said filiform thermoplasticresin including said organic anti-molding agent does not include saidinorganic anti-bacterial agent; and said filiform thermoplastic resinincluding said inorganic anti-bacterial agent does not include saidorganic anti-molding agent, such that antagonism between the two agentsis prevented.
 2. The fabric of claim 1, wherein said organicanti-molding agent is a 10, 10′ oxybisphenox-arsine anti-molding agent.3. The fabric of claim 1, wherein said inorganic anti-bacterial agent isa silver zeolite anti-bacterial agent.
 4. The fabric of claim 1, whereinsaid fabric further comprises a honeycomb weave structure.